The present invention relates to a side vehicle-body structure of a vehicle, which comprises a center pillar which includes a pillar reinforcement which is provided between a pillar outer panel and a pillar inner panel.
Conventionally, various types of vehicle-body structure of restraining deformation of the center pillar for the purpose of ensuring the safety of passengers at the vehicle side crash have been developed. For example, Japanese Patent Laid-Open Publication No. 2004-130826 discloses the structure, in which a weak portion which has a relatively low rigidity compared to the other portions is formed at a lower portion of the center pillar, a full section plastic moment stepped portion is formed at an upper portion of the center pillar so that the full section plastic moment with its center in a vehicle longitudinal direction is discontinuous, and a full section plastic moment value of the lower side portion which is below the plastic moment stepped portion is set to be higher than a full section plastic moment straight line which interconnects respective moment values of the upper end portion and the middle portion of the center pillar.
Specifically, according to the structure of the above-described publication, a second pillar reinforcement which extends over a range from the moment stepped portion to the middle portion of the center pillar is provided in addition to the normal reinforcement which is provided between the pillar outer panel and the pillar inter panel. The moment stepped portion is formed by a specified portion which corresponds to the upper end portion of this second pillar reinforcement.
The above-described structure has an advantage that since the center pillar bends at the movement stepped portion located at its upper portion and the weak portion located at its lower portion at the vehicle side crash, the center pillar can be prevented from bending at its middle portion, so that the bent center pillar may not come into the vehicle inside improperly greatly.
This structure, however, has a problem in that since the second pillar reinforcement is additionally provided to form the moment stepped portion for the purpose of causing the bend deformation at the centre pillar, the center pillar's structure would become rather complex and the whole weight of the center pillar would increase improperly as well.